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Class-d audio amplifier

a class-d, audio amplifier technology, applied in the direction of amplifier modification, low-frequency amplifier, gain control, etc., can solve the problems of reducing the noise influence of the inability to eliminate noise and imbalance, and still having pop noise in the class-d audio amplifier with a full-bridge configuration. achieve the effect of suppressing pop noise, avoiding noise, and suppressing nois

Active Publication Date: 2017-02-23
NANJING SILERGY SEMICON TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present patent introduces an auxiliary power amplifier and an auxiliary feedback circuit in a class-D audio amplifier to solve the problem of large POP noise when the system is powered on. The auxiliary close loop disconnects after circuit modules reach their steady operation points, and the system operates at a normal state. A soft start circuit is provided for suppressing noise which occurs when the system is powered on. The auxiliary power amplifier and the auxiliary feedback circuit constrain a control loop in advance to suppress POP noise at the output terminal. The system has no POP noise when powered on, thanks to the soft start circuit.

Problems solved by technology

Even so, the class-D audio amplifier with a full-bridge configuration still has POP noise to some extent.
However, the noise and the imbalance cannot be eliminated due to limitations of the process and design.
When the input voltage is a zero voltage, the output voltage still introduces a noise component and a bias voltage, and thus suffers from POP noise.

Method used

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first embodiment

[0086]FIG. 3 is an operation waveform diagram of an example class-D audio amplifier according to the present disclosure. The class-D audio amplifier will be described in detail to explain the operating principle and process of the present disclosure.

[0087]In FIG. 3, the first enable signal EN1 is the one for the power amplifier 5, i.e. an output enable signal; the second enable signal EN2 is the one for the auxiliary power amplifier 2, i.e. an auxiliary feedback enable signal, which enables the auxiliary amplifier and the auxiliary feedback circuit simultaneously in this embodiment; S5, S6, and S7 are control signals for respective ones of the switches in the soft start circuit 3; S1 and S2 are control signals for respective ones of the switches in the auxiliary feedback circuit; S3 and S4 are control signals for respective ones of the switches in the output feedback circuit; Vo is a waveform of the output voltage, i.e. a differential signal between the positive output voltage OUTP ...

second embodiment

[0101]FIG. 5 is an operation waveform diagram of an example class-D audio amplifier according to the present disclosure. The class-D audio amplifier will be described in detail to explain the operating principle and process of the present embodiment.

[0102]In FIG. 5, the signal power up is a power on signal, which is valid at a high level and indicates that the system power is enabled, the signals K1˜K6 are control signals of respective ones of the switches in the circuit diagram.

[0103]The class-D audio amplifier operates in the following sequence.

[0104]At a first stage, the system is prepared for power on.

[0105]At a second stage, the system is powered on, for supplying electric energy to various circuit modules. At the time period, the auxiliary power amplifier 6 starts to operate, the switches K1 and K2 are turned on so that the auxiliary feedback circuit is activated for feeding back an output signal of the auxiliary power amplifier 6 to an input terminal of the loop filter 1. A s...

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Abstract

The present disclosure relates to a class-D audio amplifier. When the system is powered on, an auxiliary power amplifier and an auxiliary feedback circuit constitute an auxiliary close loop so that a control loop is established in advance. The auxiliary close loop is disconnected after various circuit modules reach their steady operation points, and the system operates at a normal state. A soft start circuit is provided for suppressing noise which occurs when the system is powered on. Thus, the class-D audio amplifier suppresses POP noise at an output terminal when the system is powered on.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application claims the benefit of Chinese Patent Application No. 201510508463.3, filed on Aug. 18, 2015, which is incorporated herein by reference in its entirety.BACKGROUND OF THE DISCLOSURE[0002]Field of the Disclosure[0003]The present disclosure relates to the field of power electronics, and more particularly, to a class-D audio amplifier.[0004]Background of the Disclosure[0005]A class-D audio amplifier is widely used in portable electronic devices, such as PDA, mobile phone, MP3, and the like, because its advantages of high affiance, low power consumption.[0006]The conventional class-D audio amplifier typically introduces POP noise which is pop-like sound caused by transient impact of various operations after an audio system is powered on, powered off or operates in a steady state. The transient impact which causes POP noise is typically a narrow spike pulse. After Fourier expansion, it has complex spectral components, with energy...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): H03F1/26H04R3/02H03F1/34H03F3/187H03F3/213
CPCH03F1/26H03F3/187H03F2200/351H03F1/342H04R3/02H03F3/213H03F1/305H03F3/185H03F3/217H03F3/2171H03F3/2173H03F3/38H03F3/45475H03F2200/03H03F2200/432H03F2203/45512H03F2203/45528H03F2203/45534H03F2203/45536H03F2203/45594H03F2203/45631H03F2203/45634H03F2203/45702H03G3/348H04R2430/01
Inventor ZHU, HUAPINGCAO, HEJINSHENGWU, QICHANGSUN, ZHENGUO
Owner NANJING SILERGY SEMICON TECH CO LTD
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